U.S. patent application number 12/769001 was filed with the patent office on 2011-11-03 for subxiphoid connective lesion ablation system and method.
This patent application is currently assigned to Medtronic, Inc.. Invention is credited to Steven Bolling, Daniel Cheek, Tom Conway, Steve Ramberg, Brian Ross, James Skarda, Mitchell Strain, Randy Thill.
Application Number | 20110270243 12/769001 |
Document ID | / |
Family ID | 44120959 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110270243 |
Kind Code |
A1 |
Skarda; James ; et
al. |
November 3, 2011 |
Subxiphoid Connective Lesion Ablation System and Method
Abstract
Instrument and systems for applying ablative energy to
epicardial tissue via a subxiphoid access surgical approach. The
instrument has a head assembly sized and shaped for a subxiphoid
surgical approach to a patient's heart and defines a contact face.
The head assembly includes a paddle body, a first ablation
electrode, and a second ablation electrode. The ablation electrodes
are coupled to the paddle body in a spaced apart, spatially-fixed
fashion. The ablation electrodes are exteriorly exposed at the
contact face. A tubular member extends from the head assembly and
maintains wiring connected to the ablation electrodes. The
instrument is manipulable to locate the contact face on epicardial
tissue of a patient's heart via a subxiphoid surgical approach,
such as between the left and right pulmonary vein junctions of the
posterior left atrium.
Inventors: |
Skarda; James; (Lake Elmo,
MN) ; Bolling; Steven; (Ann Arbor, MI) ;
Cheek; Daniel; (Plymouth, MN) ; Ross; Brian;
(Maple Grove, MN) ; Strain; Mitchell; (St. Paul,
MN) ; Ramberg; Steve; (North Oaks, MN) ;
Conway; Tom; (White Bear Lake, MN) ; Thill;
Randy; (St. Paul, MN) |
Assignee: |
Medtronic, Inc.
Minneapolis
MN
|
Family ID: |
44120959 |
Appl. No.: |
12/769001 |
Filed: |
April 28, 2010 |
Current U.S.
Class: |
606/41 |
Current CPC
Class: |
A61B 18/14 20130101;
A61B 2018/00351 20130101; A61B 2018/00291 20130101; A61B 2018/00577
20130101; A61B 2018/126 20130101; A61B 2018/1497 20130101; A61B
18/1482 20130101; A61B 2018/00363 20130101; A61B 2018/1467
20130101 |
Class at
Publication: |
606/41 |
International
Class: |
A61B 18/14 20060101
A61B018/14 |
Claims
1. An ablation instrument for applying ablative energy to
epicardial tissue via a subxiphoid access surgical approach to
treat cardiac arrhythmia, the ablation instrument comprising: head
assembly sized and shaped for a subxiphoid surgical approach to a
patient's heart, the head assembly defining a contact face and
including: a paddle body defining an outer perimeter of the head
assembly, a first elongated ablation electrode, a second elongated
ablation electrode, wherein the first and second ablation
electrodes are coupled to the paddle body in a spaced apart,
electrically isolated fashion such that a spatial relationship
between the first and second ablation electrodes is fixed, the
ablation electrodes being exteriorly exposed at the contact face
and entirely within the outer perimeter; a tubular member extending
from the head assembly; and wiring electrically connected to the
first and second ablation electrodes for delivering energy to the
first and second ablation electrodes, the wiring extending through
the tubular member; wherein the instrument is manipulable to locate
the contact face on epicardial tissue of a patient's heart via a
subxiphoid surgical approach.
2. The ablation instrument of claim 1, wherein the instrument is
manipulable to locate the first and second ablation electrodes on
epicardial tissue between left and right pulmonary vein junctions
of a patient's posterior left atrium via a subxiphoid surgical
approach.
3. The ablation instrument of claim 1, wherein the paddle body
defines a leading end, a trailing end opposite the leading end, and
opposing sides, the ends combining to define a length of the head
assembly and the sides combining to define a width of the head
assembly, and further wherein the tubular member is coupled to the
trailing end.
4. The ablation instrument of claim 3, wherein a diameter of the
tubular member is less than the width of the head assembly.
5. The ablation instrument of claim 3, wherein the first and second
ablation electrodes are arranged to extend generally perpendicular
to a direction of the length.
6. The ablation instrument of claim 3, wherein the first and second
ablation electrodes are arranged to extend generally perpendicular
to a central axis of the tubular member.
7. The ablation instrument of claim 3, wherein at least the first
ablation electrode has a curved longitudinal shape.
8. The ablation instrument of claim 1, wherein the first and second
ablation electrodes are sized and arranged relative to the paddle
body such that when the head assembly is positioned along the
posterior left atrium between left and right pulmonary veins, the
ablation electrodes are operable to form lesions interconnecting
island lesions surrounding junctions of the pulmonary veins with
the left atrium.
9. The ablation instrument of claim 1, wherein the paddle body
includes: a head; a first skirt projecting from the head and
surrounding a perimeter of the first ablation electrode to define a
first suction region; a second skirt projecting from the head and
surrounding a perimeter of the second ablation electrode to
establish a second suction region; a first suction aperture formed
by the head within the first suction region for applying a suction
force to the first suction region; and a second suction aperture
formed by the head within the second suction region for applying a
suction force to the second suction region.
10. The ablation instrument of claim 9, further comprising: suction
tubing fluidly connected to each of the suction apertures and
extending through the tubular member.
11. The ablation instrument of claim 1, wherein the head assembly
further includes: first and second auxiliary electrodes coupled to
the paddle body and exteriorly exposed at the contact face; wherein
the auxiliary electrodes are electrically isolated from one another
and are located between the first and second ablation
electrodes.
12. The ablation instrument of claim 11, wherein the auxiliary
electrodes are operable to perform a pacing operation on a
patient's heart.
13. The ablation instrument of claim 11, wherein the auxiliary
electrodes are operable to sense electrical activity on a patient's
heart.
14. An ablation system for applying ablative energy to epicardial
tissue via a subxiphoid access surgical approach to treat cardiac
arrhythmia, the ablation system comprising: an ablation instrument
comprising: head assembly sized and shaped for a subxiphoid
surgical approach to a patient's heart, the head assembly defining
a contact face and including: a paddle body defining an outer
perimeter of the head assembly, a first elongated ablation
electrode, a second elongated ablation electrode, wherein the first
and second ablation electrodes are coupled to the paddle body in a
spaced apart, electrically isolated fashion such that a spatial
relationship between the first and second ablation electrodes is
fixed, the ablation electrodes being exteriorly exposed at the
contact face and entirely within the outer perimeter, a tubular
member extending from the head assembly, wiring electrically
connected to the first and second ablation electrodes for
delivering energy to the first and second ablation electrodes, the
wiring extending through the tubular member; and a power source for
providing energy to the first and second ablation electrodes via
the wiring; wherein the instrument is configured to be manipulated
to locate the contact face on epicardial tissue of a patient heart
via a subxiphoid surgical approach.
15. The ablation system of claim 14, wherein the instrument is
manipulable to locate the first and second ablation electrodes on
epicardial tissue between left and right pulmonary vein junctions
of a patient's posterior left atrium via a subxiphoid surgical
approach.
16. The ablation system of claim 14, wherein the paddle body
defines a leading end, a trailing end opposite the leading end, and
opposing sides, the ends combining to define a length of the head
assembly and the sides combining to define a width of the head
assembly, and further wherein the tubular member is coupled to the
trailing end.
17. The ablation system of claim 15, wherein the first and second
ablation electrodes are arranged to extend generally perpendicular
to a direction of the length.
18. The ablation system of claim 14, wherein the first and second
ablation electrodes are sized and arranged relative to the paddle
body such that when the head assembly is positioned between left
and right pulmonary veins of the patient's heart, the electrodes
form lesions interconnecting island lesions surrounding the
pulmonary veins.
19. The ablation system of claim 14, wherein the paddle body
includes: a head; a first skirt projecting from the head and
surrounding a perimeter of the first ablation electrode to define a
first suction region; a second flange projecting from the head and
surrounding a perimeter of the second ablation electrode to
establish a second suction region; a first suction aperture formed
by the head within the first suction region for applying a suction
force to the first suction region; and a second suction aperture
disposed within the second electrode suction region for applying a
suction force to the second electrode suction region.
20. The ablation system of claim 19, further comprising: suction
tubing fluidly connected to each of the suction apertures and
extending through the tubular member; and a negative pressure
source fluidly connected to the suction apertures via the suction
tubing.
21. The ablation system of claim 14, wherein the head assembly
further includes: first and second auxiliary electrodes coupled to
the paddle body and exteriorly exposed at the contact face; wherein
the auxiliary electrodes are electrically isolated from one another
and are located between the first and second ablation
electrodes.
22. The ablation system of claim 21, further comprising: a
controller electronically connected to the auxiliary electrodes,
the controller programmed to perform a pacing operation in which
stimulation energy is provided to the auxiliary electrodes
sufficient to pace a patient's heart, and to perform a sensing
operation in which electrical activity at the auxiliary electrodes
is sensed.
23. The ablation system of claim 22, wherein the controller is
further programmed to perform a conduction block evaluation test
via the auxiliary electrodes.
24. A method for ablating epicardial tissue on a heart of a patient
to treat cardiac arrhythmia, the method comprising: inserting an
ablation head assembly of an ablation instrument through a
subxiphoid access incision in a chest of the patient, the head
assembly defining a contact face and including: a paddle body
defining an outer perimeter of the head assembly, a first elongated
ablation electrode, a second elongated ablation electrode, wherein
the first and second ablation electrodes are coupled to the paddle
body in a spaced apart, electrically isolated fashion such that a
spatial relationship between the first and second ablation
electrodes is fixed, the ablation electrodes being exteriorly
exposed relative to the contact face and entirely within the outer
perimeter; bringing the first and second ablation electrodes into
contact with the epicardial tissue; and applying ablation energy to
the heart tissue with the first and second electrodes to destroy
one or more conduction pathways in the heart.
25. The ablation system of claim 24, further comprising: forming a
first island lesion encircling a junction of right pulmonary veins
with the left atrium of the patient's heart; and forming a second
island lesion encircling a junction of left pulmonary veins with
the left atrium of the patient's heart; wherein the step of
applying energy to the first and second ablation electrodes
includes forming first and second connective lesions each
interconnecting the first and second island lesions.
26. The ablation system of claim 25, wherein forming the first and
second connective lesions includes the head assembly not moving
relative to the patient's heart.
27. The ablation system of claim 24, wherein bringing the first and
second electrodes into contact with epicardial tissue includes
suctioning the epicardial tissue into contact with the first and
second ablation electrodes.
28. The ablation system of claim 24, further comprising: operating
auxiliary electrodes provided with the head assembly to evaluate
electrical activity along the heart tissue following the step of
applying ablation energy.
Description
BACKGROUND
[0001] Atrial fibrillation is a common cardiac condition in which
irregular heart beats cause a decrease in the efficiency of the
heart, sometimes due to variances in the electrical conduction
system of the heart. In some circumstances, atrial fibrillation
poses no immediate threat to the health of the individual suffering
from the condition, but may, over time, result in conditions
adverse to the health of the patient, including heart failure and
stroke. In the case of many individuals suffering from atrial
fibrillation, symptoms affecting the patient's quality of life may
occur immediately with the onset of the condition, including lack
of energy, fainting, and heart palpitations.
[0002] In some circumstances, atrial fibrillation may be treated
with drugs or through the application of defibrillation shocks. In
cases of persistent atrial fibrillation, however, surgery may be
required. The surgical procedure originally developed to treat
atrial fibrillation is known as a "MAZE" procedure where the atria
are surgically cut apart along specific lines and sutured back
together. While possibly effective, the MAZE procedure tends to be
complex and may require highly invasive access to the thorax. In
order to reduce the need to open the atria, thermal ablation tools
have been developed to produce lines of inactive tissue along the
heart wall that mimic the MAZE procedure. This is most commonly
done using radio frequency (RF) ablation devices to ablate and
electrically isolate tissue that may be responsible for the
improper or electrical conduction that causes atrial
fibrillation.
[0003] A variety of cardiac ablation devices and methods are
currently available for treatment of atrial fibrillation and other
arrhythmias. With some systems, endocardial tissue is contacted and
ablated, for example via a catheter-based ablation instrument.
Conversely, epicardial tissue can be ablated. Conventionally,
cardiac surgeons access the epicardial tissue via a standard
sternotomy. More recently, certain atrial fibrillation treatment
procedures have been advanced that entail ablating small segments
of epicardial tissue on a minimally invasive basis, such as via a
single or bilateral thoractomy approach. For example, the junctions
of pulmonary veins with the left atrium have been identified as
being a common area where atrial fibrillation-triggering foci
reside. For many patients, then, atrial fibrillation can be
effectively treated by ablating only a portion of the complete MAZE
pattern, such as at the pulmonary vein/left atrium junction. More
particularly, a viable cardiac arrhythmia treatment technique
entails ablating an epicardial lesion into the posterior left
atrium around or circumscribing the left pulmonary veins and
another epicardial lesion encircling the right pulmonary veins.
These island ablation lesions can be formed on a minimally invasive
basis via bilateral thoractomy using clamp-type ablation
instruments, for example a surgical ablation device available under
the trade name Cardioblate.RTM. Gemini.TM. available from
Medtronic, Inc. While well-accepted, the bilateral thoractomy
surgical approach may require the surgeon to perform various
additional procedures, such as dissection of pericardial
reflections, in order to laterally access the posterior left atrium
ablation site(s). Additionally, while the pulmonary vein island
ablation represents only a small portion of a complete MAZE
procedure, additional epicardial lesions along the left atrium may
be beneficial to prevent re-entry of an unwanted sympathetic
pathway.
[0004] In light of the above, a need exists for systems and methods
of making epicardial lesions on selected cardiac locations on a
minimally invasive basis, such as along the posterior left atrium
via a subxiphoid surgical approach.
SUMMARY
[0005] Some aspects in accordance with principles of the present
disclosure relate to an ablation instrument for applying ablative
energy to epicardial tissue via a subxiphoid access surgical
approach to treat cardiac arrhythmia. The ablation instrument
includes a head assembly, a tubular member, and wiring. The head
assembly is sized and shaped for a subxiphoid surgical approach to
a patient's heart and defines a contact face. Further, the head
assembly includes a paddle body, a first elongated ablation
electrode, and a second elongated ablation electrode. The paddle
body defines an outer perimeter of the head assembly. The first and
second ablation electrodes are coupled to the paddle body in a
spaced apart, electrically isolated fashion such that a spatial
relationship between the ablation electrodes is fixed. The ablation
electrodes are exteriorly exposed at the contact face of the head
assembly, and are maintained entirely within the outer perimeter.
The tubular member extends from the head assembly. The wiring is
electrically connected to the first and second ablation electrodes
for delivering ablative energy thereto, and extends through the
tubular member. With this construction, the ablation instrument is
manipulateable to locate the contact face at epicardial tissue of a
patient's heart via a subxiphoid surgical approach. For example,
the ablation electrodes can be located on epicardial tissue of the
posterior left atrium between the left and right pulmonary vein
junctions via a subxiphoid surgical approach. In some embodiments,
the head assembly further include one or more auxiliary electrodes
maintained between the ablation electrodes and available for
performing various pacing and/or sensing procedures. In other
embodiments, the paddle body forms suction regions about each of
the ablation electrodes. In other, possibly related embodiments,
the head assembly incorporation irrigation delivery features for
supplying an irrigation liquid (e.g., saline) that effectuates
cooling of the ablation electrodes; the so-delivered liquid can
then be evacuated from the head assembly through the suction
regions.
[0006] Yet other aspects of the present disclosure relate to an
ablation system for applying ablative energy to epicardial tissue
via a subxiphoid access surgical approach to treat cardiac
arrhythmia. The ablation system includes the ablation instrument as
described above and a power source for providing ablative energy to
the ablation electrodes. In some constructions, the system further
includes a controller electronically connected to auxiliary
electrodes carried by the paddle body, with the controller being
programmed to perform pacing and sensing procedures via the
auxiliary electrodes to evaluate effectiveness of a conductive
block lesion pattern.
[0007] Yet other aspects in accordance with principles of the
present disclosure relate to a method for ablating epicardial
tissue of a patient to treat cardiac arrhythmia. The method
includes inserting an ablation head assembly of an ablation
instrument through a subxiphoid access incision in a chest of the
patient. The head assembly defines a contact face and includes a
paddle body and two elongated ablation electrodes. The ablation
electrodes are coupled to the paddle body in a spaced apart,
electrically isolated fashion such that a spatial relationship
between the first and second ablation electrodes is fixed. The
ablation electrodes are exteriorly exposed relative to the contact
face and entirely within an outer perimeter defined by the paddle
body. Following subxiphoid insertion, the head assembly is directed
to bring the ablation electrodes into contact with the epicardial
tissue. Ablation energy is then applied to the heart tissue via the
ablation electrodes to destroy one or more conduction pathways in
the heart. In some embodiments, the method is performed as part of
a partial MAZE procedure in which first and second island lesion
ablation patterns are formed about junctions of the right pulmonary
veins and the left pulmonary veins with the left atrium of the
patient's heart. With this in mind, the ablation lesions formed by
the ablation electrodes interconnect the island lesions in forming
a conductive block along the posterior left atrium. In other
embodiments, conductive block testing is performed via the head
assembly immediately following the formation of the connective
lesions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view, with portions shown in block
form, of an ablation system useful for applying ablative energy to
epicardial tissue via a subxiphoid surgical approach in accordance
with principles of the present disclosure;
[0009] FIG. 2 is an exploded, perspective view of a surgical
instrument component of the system of FIG. 1;
[0010] FIG. 3 is an enlarged, perspective view of a head assembly
portion of the instrument of FIG. 2;
[0011] FIG. 4 is a top plan view of the head assembly of FIG.
3;
[0012] FIG. 5 is an exploded, perspective view of the head assembly
of FIG. 3, along with other components of the instrument of FIG.
2;
[0013] FIG. 6A is a top plan view of a head component of the head
assembly of FIG. 5;
[0014] FIG. 6B is a bottom plan view of the head component of FIG.
6A;
[0015] FIG. 7 is a exploded, perspective view illustrating assembly
of various components of the head assembly of FIG. 3;
[0016] FIG. 8 is a simplified representation of various anatomy of
a patient's chest;
[0017] FIG. 9A is a posterior view of a human heart;
[0018] FIG. 9B is a posterior view of the human heart of FIG. 9A
and illustrating island lesion patterns formed about junctions
between pulmonary veins and left atrium;
[0019] FIGS. 10A-10E illustrate methods in accordance with the
present disclosure including the ablation system of FIG. 1 employed
to complete a portion of a conductive block ablation pattern on the
posterior left atrium via a subxiphoid surgical approach; and
[0020] FIGS. 11A-11R are simplified plan views of other head
assemblies in accordance with the present disclosure and useful
with the ablation instrument of FIG. 2.
DETAILED DESCRIPTION
[0021] One embodiment of an ablation system 20 in accordance with
aspects of the present disclosure and useful for applying ablative
energy to epicardial tissue via a subxiphoid surgical approach is
shown in FIG. 1. The ablation system 20 includes an ablation
instrument 22 and a power source 24. Optionally, additional
components can be provided with the ablation system 20, such as a
controller 26 (provided with or apart from the power source 24), a
vacuum or negative pressure source 28, a liquid source 30, and an
indifferent or grounding electrode 32. Details on the various
components are provided below. In general terms, however, the
instrument 22 includes a head assembly 40 sized and shaped for
accessing epicardial tissue of a patient's heart (e.g., along the
posterior left atrium between the left and right pulmonary veins
junctions) via a subxiphoid incision in the patient's chest. The
head assembly 40 carries various electrodes that, when energized
via the power source 24, ablate contacted cardiac tissue to form a
corresponding, desired lesion pattern. The controller 26 optionally
facilitates performance of various testing procedures with the head
assembly 40, such as pace/sense protocols. The optional vacuum
source 28 can be employed to draw tissue into more intimate contact
with the electrodes carried by the head assembly 40, whereas the
optional liquid source 30 can facilitate cooling of the head
assembly 40. Regardless, the ablation system 20, and in particular
the instrument 22, can be employed on a minimally invasive basis
via a subxiphoid surgical approach, uniquely serving to complete a
portion of a MAZE lesion pattern, such as interconnecting or
otherwise completing a conduction block between island lesion
patterns formed on the posterior left atrium about the left and
right pulmonary veins.
[0022] With additional reference to FIG. 2, the ablation instrument
22 includes the head assembly 40, a tubular member 42, and a handle
assembly 44 (referenced generally). The tubular member 42
supportively connects the head assembly 40 with the handle assembly
44, and provides a protective conduit for wiring and tubing or
similar structures (e.g., a suction tube, liquid tube, etc.), to
and from the head assembly 40. The handle assembly 44, in turn,
promotes handling and operation of the instrument 22, including
connecting the instrument 22 with the power source 24 (FIG. 1) and
facilitating user control over various operations (e.g., delivery
of negative pressure and/or cooling liquid to the head assembly
40).
[0023] The head assembly 40 is shown in greater detail in FIG. 3,
and generally includes a paddle body 50, a first elongated ablation
electrode 52, and a second elongated ablation electrode 54. The
ablation electrodes 52, 54 are mounted to the paddle body 50 in a
spaced apart, fixed manner, with the paddle body 50 optionally
forming suction regions or pods about the ablation electrodes 52,
54, respectively. The paddle body 50 can maintain additional
components, such as cooling liquid delivery tubing and/or first and
second auxiliary electrodes 56, 58 (e.g., for performing pacing
and/or sensing procedures as described below).
[0024] The paddle body 50 can assume various forms conducive to
subxiphoid insertion and for maintaining the ablation electrodes
52, 54. In more general terms, and as reflected in FIG. 4, the
paddle body 50 defines an outer perimeter 60 of the head assembly
40, including a leading end 62, a trailing end 64, and opposing
sides 66, 68. Connection of the head assembly 40 with the tubular
member 42 (FIG. 2) is provided at the trailing end 64, with the
leading end 62 serving as a distal-most end of the instrument 22
(FIG. 2). The leading and trailing ends 62, 64 combine to define a
length L of the head assembly 40. The opposing sides 66, 68 combine
to define a maximum width W of the head assembly 60. With these
designations in mind, a shape of the outer perimeter 60, as well as
dimensions of the length L and the maximum width W are sized for
subxiphoid insertion, as well as, in some embodiments, to nest
between the left and right pulmonary veins at the epicardial
surface of the posterior left atrium of an adult human heart. As
made clear below, a width of the paddle body 50 is a function of
the lengths of the ablation electrodes 52, 54, with these lengths
being selected, in some embodiments, to traverse the lateral
distance between the junction of the left pulmonary veins with the
left atrium and the junction of the right pulmonary veins with left
atrium at superior and inferior locations. With these embodiments,
then, a width of the paddle body 50 generally coincides with the
typical left atrium pulmonary vein junction spacing. Other
procedures, and thus other shapes and/or sizes, are also
envisioned. While the paddle body 50 is reflected as having a
generally trapezoidal perimeter shape, other configurations are
also acceptable. For example, while the paddle body 50 is shown as
tapering in width from the trailing end 64 to the leading end 62,
other shapes are also envisioned (e.g., a more rectangular shape,
circular shape, etc.). Regardless, to promote subxiphoid insertion
in combination with spanning the pulmonary vein junction distance
at the left atrium of a typical adult human heart, the maximum
width W of the paddle body 50 can be in the range of 3-7 cm, and
the length L can be in the range of 4-12 cm.
[0025] The paddle body 50 can be constructed as a single,
homogeneous piece. Alternatively, a mere complex assembly can be
utilized. For example, FIG. 5 illustrates that in some embodiments,
the paddle body 50 includes a base 70 and a head 72. With this but
one acceptable construction, the head 72 is sized and shaped for
assembly to the base 70, with the head 72 providing various
features adapted for mounting of the ablation electrodes 52, 54 as
described below.
[0026] The base 70 can include or define a neck region 80, a floor
82, and a sidewall 84. A trough 86 is formed along the neck region
80 and extends to a chamber 88 formed in the floor 82. The trough
86 and the chamber 88 provide an isolated pathway for various wires
and/or tubes upon assembly of the head 72 to the base 70. A suction
channel 90 is also formed in the floor 82, and provides a sealed
passageway for application negative pressure upon final assembly.
In this regard, a track 92 can be formed in the floor 82 about the
suction channel 90 and configured to sealingly receive a
corresponding feature (e.g., a similarly shaped rib) provided with
the head 72. Other assembly configurations are also acceptable that
may or may not include the track 92. Finally, the sidewall 84
projects from an outer perimeter of the floor 82, serving to define
the outer perimeter 60 (FIG. 4) of the paddle body 50. The base 70
can be formed from various surgically safe materials, and in some
embodiments is a molded material that is free of sharp corners for
atraumatic insertion into the human body. For example, the base 70
can be a relatively soft polymer such as 72 Durometer urethane. A
wide variety of other surgically safe materials (e.g., metals) are
also acceptable.
[0027] The head 72 can include a neck region 100 and a platform
102. The neck region 100 is sized for mating with the neck region
80 of the base 70. Similarly, the platform 102 is sized and shaped
for assembly to the floor 82, nesting within the sidewall 84. In
some constructions, the platform 102 defines a leading segment 104
and a trailing segment 106. As shown, the leading segment 104 can
be recessed below the trailing segment 106 (relative to the
orientation of FIG. 5). Regardless, the leading segment 104 forms a
first slot 108 and a second slot 110. With additional reference to
FIG. 6A, the first slot 108 is generally sized and shaped in
accordance with (e.g., slightly larger than) the first ablation
electrode 52, whereas the second slot 110 is sized and shaped to
receive the second ablation electrode 54. To facilitate mounting of
the ablation electrodes 52, 54 within the respective slots 108,
110, the leading segment 104 can include or form one or more
fingers 112, 114 within each of the slots 108, 110, with the
fingers 112, 114 being configured to receive and support a segment
of the corresponding ablation electrode 52, 54. In some
constructions, the fingers 112, 114 are adapted to frictionally
retain the corresponding ablation electrode 52, 54 (e.g., press-fit
mounting), although other mounting techniques are also envisioned
(e.g., adhesive bond). With the but one acceptable construction of
FIG. 6A, one or more of the fingers 112, 114 associated with each
of the slots 108, 110 can form a longitudinal through hole
(referenced generally at 116 for one of the fingers 112 of the
first slot 108 and for one of the fingers 114 of the second slot
110) that facilitates the passage of wiring from the corresponding
ablation electrode 52 or 54 as described below.
[0028] An irrigation hole 120a and/or a suction aperture 122a can
optionally be formed in the leading segment 104, fluidly open to
the first slot 108; a similar irrigation hole 120b and/or suction
aperture 122b can be formed in, and fluidly open to, the second
slot 110. Where provided, the irrigation holes 120a, 120b provide a
passageway for a liquid delivery tube (not shown) into the
corresponding slot 108, 110. The optional suction apertures 122a,
122b fluidly connect a negative pressure source to the
corresponding slot 108, 110. For example, as best shown in FIG. 6B,
the suction apertures 122a, 122b are fluidly open to a rear face
124 of the head 72. A rib 126 projects from the rear face 124, and
surrounds the suction apertures 122a, 122b, as well as a channel
128. The rib 126 is sized to be received within the track 92 (FIG.
5) of the base 70 (FIG. 5), with the channel 128 being fluidly
connected to a bore 130 (hidden in FIG. 6B, but shown generally in
FIG. 5) in a thickness of the neck region 100. Upon assembly of the
base 70 and the head 72 and connection of vacuum tubing (not shown)
to the bore 130, negative pressure (e.g., generated by the vacuum
source 30 (FIG. 1)) through the bore 130 is applied to the channel
128 of the head 72. The suction channel 90 (FIG. 5) of the base 70
is fluidly connected to the suction channel 128 of the head 72, as
well with the suction apertures 122a, 122b, thereby delivering
negative pressure to the slots 108, 110 (FIG. 6A). Assembly of the
rib 126 within the track 92 fluidly isolates the negative pressure
pathway.
[0029] Returning to FIGS. 5 and 6A, in some embodiments, the head
72 is further adapted to receive one or more other components in
addition to the ablation electrodes 52, 54. For example, with
embodiments in which the optional auxiliary electrodes 56, 58 are
provided, the leading segment 104 can further form or define first
and second auxiliary holes 140, 142. The holes 140, 142 are
generally configured to facilitate passage of wiring (not shown)
extending from the corresponding auxiliary electrodes 56, 58, and
serve to desirably locate the auxiliary electrodes 56, 58 relative
to the ablation electrodes 52, 54 upon final assembly. In
particular, and for reasons made clear below, the auxiliary
electrodes 56, 58 are positioned between the first and second
ablation electrodes 52, 54 and at a sufficient distance relative to
one another to perform desired operations, such as pacing and/or
sensing.
[0030] With specific reference to FIG. 5, the paddle body 50 can
further include, in some constructions, an optional tissue contact
member 150 that is mounted to the leading segment 104 of the head
72. The tissue contact member 150 is generally constructed for
atraumatic interface with cardiac tissue, and forms or defines a
first skirt 152 and a second skirt 154. The skirts 152, 154 project
upwardly from a panel 156 (relative to the orientation of FIG. 5),
with the first skirt 152 being generally sized and shaped in
accordance with the first ablation electrode 52, and the second
skirt 154 being generally sized and shaped in accordance with the
second ablation electrode 54. As described below, the skirts 152,
154 establish suction regions or pods 158, 160 relative to the
corresponding ablation electrodes 52, 54, with the panel 156
forming openings 162, 164 through a thickness thereof and through
which negative pressure established at the first and second suction
apertures 122a, 122b (FIG. 6A), respectively, is conveyed to the
suction regions 158, 160. With configurations in which the
auxiliary electrodes 56, 58 are provided, the tissue contact member
150 forms or defines first and second auxiliary openings 166, 168
configured to maintain a corresponding one of the auxiliary
electrodes 56, 58.
[0031] In some constructions, the tissue contact member 150 is
formed by a first, support layer 170 and a second, skirt layer 172.
The support layer 170 generally reinforces the tissue contact
member 150, and can be formed of a relatively stiffer material than
that of the skirt layer 172. The skirt layer 172 can be over-molded
to the support layer 170, and defines the first and second skirts
152, 154. For example, in some embodiments, the support layer 170
is a 72 Durometer urethane material, whereas the skirt layer 152 is
a 42 Durometer polyurethane material. Other materials and/or
constructions are also acceptable. In yet other embodiments, one or
both of the skirts 152, 154 can be integrally formed or defined by
the head 72. Where provided, the skirts 152, 154 can be compliant
or resiliently deflectable at expected negative pressure levels
(e.g., in the range of -100 mm Hg to -400 mm Hg) to promote
atraumatic interface with contacted cardiac tissue. That is to say,
the skirts 152, 154 will somewhat collapse (e.g., elastically) in
the presence of expected negative pressure levels to ensure
consistent, intimate contact of the tissue to be ablated with the
corresponding ablation electrode 52, 54, In yet other embodiments,
one or both of the skirts 152, 154 can be omitted.
[0032] The first ablation electrode 52 can assume various forms
appropriate for delivering RF energy at sufficient levels for
ablating contacted epicardial tissue. For example, the first
ablation electrode 52 can be an electrically conductive metal such
as 304 stainless steel. In some embodiments, the first ablation
electrode 52 is a solid shaft or wire; in other embodiments a
tubular construction can be employed. Regardless, the first
ablation electrode 52 is generally elongated (e.g., having a
longitudinal length at least three times greater than a width or
diameter thereof), and can have a slight curvature along an
intermediate segment 174 thereof. Further, opposing ends 176, 178
of the first ablation electrode 52 can extend inwardly relative to
the intermediate segment 174 as shown. Other shapes are also
acceptable. One or more sensing-type components (e.g.,
thermocouple, transistor, etc.) can optionally be assembled to or
formed by the first ablation electrode 52. For example, separate
thermocouples (not shown) are provided at each of the ends 176,
178.
[0033] The second ablation electrode 54 is constructed of materials
similar to those described above with respect to the first ablation
electrode 54, and in some embodiments is a solid metal wire or
shaft. With the but one acceptable construction of FIG. 5, the
second ablation electrode 54 is generally elongated, having a
relatively continuous, planar curve extending between opposing ends
180, 182 and defining a radius of curvature that is less than that
of the intermediate segment 174 of the first ablation electrode 52.
Other shapes are also envisioned. For example, the ablation
electrodes 52, 54 can have identical shapes. Regardless, one or
more sensing elements (e.g., thermocouple, transistor, etc.) can be
provided with the second ablation electrode 54, for example at one
or both of the ends 180, 182.
[0034] The optional auxiliary electrodes 56, 58 can be identical,
and can assume any conventional form appropriate for performing the
pacing and/or sensing protocols described below. Thus, the
auxiliary electrodes 56, 58 can be electrically conductive metal
buttons.
[0035] Construction of the head assembly 40 includes mounting of
the ablation electrodes 52, 54, the auxiliary electrodes 56, 58,
and the tissue contact member 150 to the head 72 as shown in FIG.
7. The first ablation electrode 52 is mounted within the first slot
108 via the fingers 112. In this regard, a primary wire 190 is
electrically connected to the first ablation electrode 52, and is
threaded through the through hole 116 in one of the fingers 112.
One or more secondary wires 192 can also be provided, and
electrically connected to sensing elements (e.g., thermocouples)
carried by the first ablation electrode 52. Where provided, the
secondary wires 192 are threaded through holes 116 of corresponding
ones of the fingers 112. The second ablation electrode 54 is
similarly mounted within the second slot 110, with a primary wire
194 and optional secondary wires 196 (e.g., with embodiments in
which the second ablation electrode 54 carries thermocouples or
other sensing-type components) electrically connected to the second
ablation electrode 54 and passed through holes 116 in corresponding
ones of the fingers 114. The optional first auxiliary electrode 56
is electrically connected to a first sensor wire 198 that in turn
is inserted through the first auxiliary opening 166 in the tissue
contact member 150 and the first auxiliary hole 140 (hidden in FIG.
7) in the head 72. Similarly, a second sensor wire 200, otherwise
electrically connected to the second auxiliary electrode 58, is
passed through the second auxiliary opening 168 in the tissue
contact member 150 and the second auxiliary hole 142 in the head
72. Finally, the tissue contact member 150 is mounted to the head
72 such that the first skirt 152 surrounds the first ablation
electrode 52 and the second skirt 154 surrounds the second ablation
electrode 54.
[0036] Though not shown in FIG. 7, liquid lines or tubes 204, 206
(FIG. 5) are located along the rear face 124 (FIG. 6B) of the head
72 and inserted into respective ones of the irrigation holes 120a,
120b (best shown in FIG. 6A) so as to be fluidly open to the
corresponding slot 108, 110. Similarly, a vacuum line or tube (not
shown) is fluidly connected to the bore 130. The head 72 is then
assembled to the base 70 (FIG. 5). The various wires 190-200 and
tubes 204, 206 are fed through the chamber 88 and along the trough
86 for subsequent insertion through the tubular member 42.
[0037] Final construction of the head assembly 40 with the tubular
member 42 is shown in FIG. 3. The first and second ablation
electrodes 52, 54 are exteriorly exposed relative to a contact face
210 of the head assembly 40. As used in this specification, the
"contact face" is in reference to a side or surface of the head
assembly 40 intended to be brought into contact with tissue to be
ablated. While the skirts 152, 154 project outwardly beyond the
corresponding ablation electrodes 52, 54, the suction regions or
pods 158, 160 are exteriorly open such that the ablation electrodes
52, 54 are exteriorly exposed and can be brought into ablative
contact with tissue otherwise abutting the contact face 210. FIG. 3
further reflects that the optional auxiliary electrodes 56, 58 are
exteriorly exposed at the contact face 210, and are located between
the ablation electrodes 52, 54. As made clear below, during use of
the ablation instrument 22, the ablation electrodes 52, 54 are
operable to complete a desired conductive block pattern. By
locating the auxiliary sensing electrodes 56, 58 between the
ablation electrodes 52, 54, the ablation instrument 22 can further
be employed to evaluate a completeness of the so-formed conductive
block pattern immediately after the ablation steps are complete and
without movement of the contact face 210 relative to the target
site.
[0038] As described above, the paddle body 50 is sized and shaped
for accessing various anatomical locations, such as epicardial
tissue at the posterior left atrium, via a subxiphoid surgical
approach. The size and shape of the paddle body 50 facilitates this
implementation. As such, while the ablation electrodes 52, 54 are
generally elongated, the terminal ends thereof do not project
beyond the outer perimeter 60 of the paddle body 50. Instead, the
ablation electrodes 52, 54 are arranged within a footprint of the
paddle body 50, and thus are readily positioned at a desired target
site via a subxiphoid surgical approach, for example along
epicardial tissue of the posterior left atrium at superior and
inferior aspects of the pulmonary vein junction spacing.
[0039] Returning to FIG. 5, the tubular member 42 is generally
configured to house various lines and wiring extending from the
head assembly 40. In general terms, the tubular member 42 has an
outer diameter appropriate for subxiphoid placement, and a length
sufficient to deliver the head assembly 40 to the posterior left
atrium via a subxiphoid incision. In some constructions, the
tubular member 42 is a corrugated tube, such as a stainless steel
corrugated tube. Thus, the tubular member 42 is at least somewhat
malleable, capable of self-maintaining a desired shape. A distal
end 212 of the tubular member 42 is configured for attachment to
the head assembly 40, for example via one or more internal
shoulders 214 (referenced generally) configured to be captured by a
corresponding feature of the paddle body neck regions 80, 100.
Other mounting configurations are equally acceptable. A proximal
end 216 of the tubular member 42 is similarly constructed for
mounting to the handle assembly 44 (FIG. 2). Regardless, a lumen
218 is defined through the tubular member 42, serving as a conduit
for various components extending from the head assembly 40.
[0040] With reference to FIG. 2, the handle assembly 44 can assume
various forms, and in some constructions includes a housing 220
(referenced generally), an actuator mechanism 222, and a connector
224. In general terms, the housing 220 is coupled to the tubular
member 42, and maintains the actuator mechanism 222. The actuator
mechanism 222, in turn, operates to control fluid flow through the
liquid tubes 204, 206 and the vacuum line or tube (not shown).
Finally, the connector 224 extends from the housing 220 and
facilitates connection to the power source 24/controller 26 (FIG.
1), and the vacuum source 28 (FIG. 1), and the liquid source 30
(FIG. 1).
[0041] The housing 220 is sized and shaped for convenient handling
by a user. In some embodiments, the housing 220 is formed by first
and second shell portions 230, 232 that are mateable to one another
in a manner capturing the proximal end 216 of the tubular member
42. The actuator mechanism 222 includes a lever or trigger 240 that
is pivotably coupled to the housing 220. A catch 242 captures the
liquid tubes 204, 206 and the vacuum tube (not shown) relative to
an engagement feature 244 of the lever 240. In a normal or first
position of the lever 240 relative to the housing 220, the
engagement feature 244 applies a pinching force to the liquid tubes
204, 206 and the vacuum tube, thereby preventing fluid flow
therethrough. Conversely, in a second, user-actuated position of
the lever 240 relative to the housing 220, the engagement feature
244 is spaced from the liquid and vacuum tubes 204, 206 to permit
fluid flow therethrough. A biasing member 246 (e.g., spring) biases
the lever 240 to the normal position relative to the housing 220.
Other fluid flow control mechanisms can alternatively be employed.
Further, while in some embodiments the delivery of power to the
ablation electrodes 52, 54 is controlled by an actuator (not shown)
apart from the handle assembly 44 (e.g., a footswitch), in other
constructions the handle assembly 44 can facilitate user control
over application of ablative energy.
[0042] The connector 224 can be an extruded tubing-type component,
providing one or more passageways 250 through which various items
can pass. For example, a first passageway 250a serves as a cabling
pathway and through which the various wires (not shown) extending
from the head assembly 40 as described above are maintained. A
second passageway 250b serves as an aspiration or negative pressure
pathway, and is fluidly connected to the vacuum line (not shown)
described above. Finally, a third passageway 250c serves as a
liquid delivery conduit and through which liquid irrigation (e.g.,
saline) is delivered to the liquid tubes 204, 206.
[0043] The handle assembly 44 can optionally incorporate one or
more additional features. For example, an indicator device 260 can
be maintained by the housing 220, and includes, for example, a
light source 262 (e.g., an RGB LED) and a lens 264. As described
below, the indicator device 260 is electronically connected to the
controller 26 (FIG. 1) and operates to provide a user with a visual
indication of various procedural parameters (e.g., the indicator
device 260 emits a green colored light when conduction block has
been achieved, and a red colored light when conduction block
criteria have not been met).
[0044] Returning to FIG. 1, the power source 24 can assume various
forms, and generally includes an RF energy generator appropriate
for supplying sufficient energy to ablate epicardial tissue. For
example, the generator provided with the power source 24 can be an
ablation energy generator available from Medtronic, Inc., under the
trade name Cardioblate.RTM. Model 68000 Generator.
[0045] In addition to the generator, the power source 24 can
include or be operatively connected to the controller 26 that
includes a computer or other logic circuitry capable of
effectuating one or more of the testing procedures or protocols
described below (e.g., hardware or software programs). For example,
the controller 26 can be akin to a model 2090/2290
Programmer/Analyzer available from Medtronic, Inc. As used through
this specification, then, reference to a "controller" includes a
single controller or two or more electronically linked controllers
or computing devices.
[0046] With cardiac ablation procedures in accordance with some
aspects of the present disclosure, radio frequency energy is
employed, with the ablation instrument 22 (and the corresponding
power source 24) adapted to deliver a maximum of 30 watts of power
at 500 kilohertz for two minutes. Other ablation parameters (e.g.,
energy type, voltage, current, frequency, etc.), can alternatively
be employed. The controller 26 can be programmed with one or more
algorithms known in the art for monitoring power and/or impedance
values at the ablation electrodes 52, 54 throughout an ablation
procedure for safety purposes.
[0047] One optional testing protocol provided with the controller
26 is a pacing procedure. In general terms, the heart is "paced" by
a low frequency signal from an external energy source to control
the beating rate of the heart. Typically, a beating rate of 20-30
beats per minute faster than the patient's then-current heart rate
is chosen. When the heart rate is controlled by the external energy
source, the pacing is considered to have "captured" control of the
heart. With this in mind, the controller 26 can be programmed to
perform a pacing protocol by causing stimulating or pacing energy
to be delivered to the auxiliary electrodes 56, 58, effectively
electrically coupling the auxiliary electrodes 56, 58 so that
energy passes between the auxiliary electrodes 56, 58. In this
regard, the controller 26 can deliver pacing energy from the power
source 24. Alternatively, the pacing energy can be generated by an
auxiliary energy source (not shown), such as an external temporary
pacemaker (e.g., an external temporary pacemaker available from
Medtronic, Inc., under Model 5348 or Model 5388).
[0048] In some configurations, a pacing threshold is less than 10
mA at 0.5 msec using Medtronic's Model 5388 temporary pacemaker. In
the context of use on cardiac tissue, if the heart does not respond
to an initial pulsed current, the current may be increased until
the heart rate responds to the stimulation. The stimulation or
pacing energy can be increased or decreased to attain capture where
desired. For example, a pacing amplitude in the range of 0.1-10.0
volts and a current in the range of 0.1-24 milliamp can be
provided.
[0049] Yet another optional non-ablation procedure available with
some embodiments of the controller 26 is a sensing protocol in
which electrical activity propagating along cardiac tissue is
monitored or sensed. With the auxiliary electrodes 56, 58 placed
into contact with desired cardiac tissue, the controller 26
effectively establishes an electrical coupling between the
auxiliary electrodes 56, 58, for example by operating the first
auxiliary electrode 56 as a positive pole and the second auxiliary
electrode 58 as a negative pole (or vice-versa). In contrast to the
pacing application, however, the controller 26 does not deliver
energy to the auxiliary electrodes 56, 58. Instead, an electrical
signal (typically a voltage measurement) progressing across the
auxiliary electrodes 56, 58 is monitored. For example, intrinsic
electrical activity across contacted tissue (e.g., a depolarizing
wave) will progress from the first auxiliary electrode 56 to the
second auxiliary electrode 58 (or vice-versa). As the depolarizing
wave progresses from the first auxiliary electrode 56 to the second
auxiliary electrode 58 (or vice-versa), the controller 26 (or an
electronically-linked analyzer) monitors or senses the changing
electrical signal(s), and can record or otherwise note various
attributes.
[0050] The optional vacuum source 28 can assume a variety of forms
appropriate for generating desired negative pressure levels. For
example, the vacuum source 28 can be a pump. Alternatively, a
wall-mounted vacuum source conventionally available in many
hospital operating rooms can be utilized.
[0051] The optional liquid source 30 can also assume any
conventional form. For example, the liquid source 30 can be a
flexible bag of liquid saline. Alternatively, a mechanized pump can
be included.
[0052] The ablation system 20 can be employed to perform various
tissue ablation procedures. One such procedure relates to the
treatment of cardiac arrhythmia, and in particular atrial
fibrillation, by forming lesions on epicardial tissue of the
patient. With this in mind, FIG. 8 is a simplified representation
of the relevant anatomy of a patient (from an anterior
perspective), reflecting a location of the heart H relative to the
patient's chest C, including the sternum ST and ribcage R. A
xiphoid process XP projects from the ribcage R. The heart H is
arranged relative to the chest C such that right pulmonary veins
RPVs and left pulmonary veins LPVs are posterior and superior. A
posterior view of the heart H is generally reflected in FIG. 9A,
and illustrates the right pulmonary veins RPVs and the left
pulmonary veins LPVs entering into the top of the left atrium LA.
The vena cava VC and aorta A are also shown. With these
designations in mind, one cardiac arrhythmia treatment method
entails, prior to use of the ablation instrument 22 (FIG. 1),
forming a first ablation lesion pattern 270 into the left atrium LA
around or encircling the left pulmonary veins LPVs (i.e., the
junction of the left pulmonary veins LPVs with the left atrium LA)
and a second ablation lesion pattern 272 around the right pulmonary
veins RPVs as reflected in FIG. 9B. The first and second ablation
patterns 270, 272 are commonly referred to as "island patterns,"
and can be formed in various manners, for example via a clamp-type
surgical ablation device available from Medtronic, Inc, under the
trade name Cardioblate.RTM. Gemini.TM.. Regardless, the ablation
instrument 22 is then employed to form lesion patterns along
epicardial tissue of the posterior left atrium LA that
interconnects the islands 270, 272.
[0053] In particular, and with reference to FIG. 10A, an incision
280 is formed immediately beneath the xiphoid process XP, thereby
establishing a subxiphoid access or surgical approach to the heart
H. As a point of reference, the subxiphoid incision 280 may have
been previously formed, for example in connection with the
formation of the island ablation patterns described above. The
ablation instrument 22 is then manipulated to position the head
assembly 40 (FIG. 2) against the posterior left atrium LA as shown
in FIG. 10B. In particular, the head assembly 40 is inserted
through the subxiphoid incision 280, and directed posteriorly and
superiorly about a posterior aspect of the heart H. The malleable
nature of the tubular member 42 in some embodiments affords the
surgeon the ability to accommodate various anatomical obstacles
presented by the particular patient. Regardless, and as shown in
FIG. 10C, the head assembly 40 is positioned such that the contact
face 210 (hidden in FIG. 10C, but shown, for example, in FIG. 3)
abuts epicardial tissue of the posterior left atrium LA.
[0054] The vacuum source 28 (FIG. 1) is then activated. With the
additional reference to FIG. 10D, negative pressure is thereby
established at the first and second suction regions 158, 160,
drawing epicardial tissue T of the posterior left atrium LA into
intimate contact with the corresponding ablation electrodes 52, 54.
Though not fully illustrated in FIG. 10D, in some embodiments the
skirts 152, 154 will elastically collapse or deflect in the
presence of negative pressure in the suction regions 158, 160,
effectively establishing a consistent holding force of the
epicardial tissue T along, and in intimate contact with, the
corresponding ablation electrodes 52, 54. The ablation electrodes
52, 54 are evenly pressed against the targeted tissue T. The power
source 24 (FIG. 1) is then activated in a manner to deliver
ablative energy to the first ablation electrode 52 for a time
sufficient to ablate the contacted tissue. The second ablation
electrode 54 is sequentially energized by the power source 24 for a
time sufficient to ablate contacted tissue. By providing the
intimate, consistent or uniform contact between the targeted tissue
T and the ablation electrodes 52, 54 as described above,
predictable ablations (in terms of, for example, transmurality,
conduction block, etc.) can be achieved. The ablation electrodes
52, 54 can be sequentially operated in any order, or can be
simultaneously energized. For safety purposes, the temperature of
the ablation electrodes 52, 54 can be closely monitored by the
controller 26 (FIG. 1), for example by electrical connection to the
optional thermocouples carried by the ablation electrode ends 176,
178, 180, 182 (FIG. 5). The liquid source 30 (FIG. 1) can be
simultaneously activated to irrigate and cool the ablation
electrodes 52, 54. For example, the liquid source 30 and the vacuum
source 28 can be fluidly connected to the head assembly 40 in
tandem. The irrigation or cooling liquid (e.g., cooled or room
temperature saline) enters the suction regions 158, 160 and cools
the corresponding ablation electrode 52, 54; the now-heated liquid
is subsequently evacuated from the suction regions 158, 160 via the
suction apertures described above. Notably, when the head assembly
40 is positioned at the target site (e.g., posterior left atrium)
and suction applied, the clinician can optionally perform a
"hands-free" ablation, allowing the clinician to complete other
tasks while the ablation is taking place. Regardless, operation of
the instrument 22 results in first and second connective ablation
lesions 290, 292 as shown in FIG. 10E.
[0055] The connective lesions 290, 292 interconnect the island
patterns 270, 272, thereby establishing a conductive block or "box"
area 294 between junctions of the left pulmonary veins LPVs and the
right pulmonary veins RPVs with the left atrium LA. As reflected in
FIG. 10E, the necessary length of the first connective lesion 290
(i.e., sufficient to extend from and between the first island 270
and the second island 272 at an inferior aspect thereof)
corresponds with a length of the first ablation electrode 52 (FIG.
4), whereas a length of the second connective lesion 292 (i.e.,
sufficient to interconnect the first and second islands 270, 272
along a superior aspect thereof) corresponds with a length of the
second ablation electrode 54 (FIG. 4). Thus, the desired connective
lesions 290, 292 are formed by the ablation instrument 22 without
requiring movement of the head assembly 40 once the delivery of
ablative energy has been initiated. In other embodiments, however,
the ablation instrument 22 can be operated to form a first segment
of the first and second connective lesions 290, 292, and then moved
transversely relative to the heart H to form corresponding second
segments of the connective lesions 290, 292.
[0056] In some embodiments, the system 20 (FIG. 1) can further be
operated to confirm successful completion of the connective lesions
290, 292 (i.e., that the conductive block 294 is electrically
isolated). For example, the controller 26 (FIG. 1) can be operated,
or caused to be operated, to perform pacing and/or sensing
procedures immediately following delivery of ablative energy to the
ablation electrodes 52, 54. To this end, by desirably positioning
the auxiliary electrodes 56, 58 spatially between the ablation
electrodes 52, 54, the auxiliary electrodes 56, 58 will inherently
be located "within" the confines of the conductive block 294. Thus,
the auxiliary electrodes 56, 58 are properly located for desired
conduction block testing upon initial placement (i.e., immediately
prior to ablating with the ablation electrodes 52, 54) of the
contact face 210 (FIG. 3) against the posterior left atrium LA; as
such, testing can be performed immediately following completion of
the connective lesions 290, 292, and the surgeon is not required to
re-position the head assembly 40. With the head assembly 40
remaining in the same location relative to the epicardial tissue T
(as in FIGS. IOC and 10D), the controller 26 operates the auxiliary
electrodes 56, 58 in a bipolar mode to perform pacing test(s)
(i.e., delivering the pacing energy as described above). For
example, as part of an exit block test, pacing energy is applied
"within" the conductive block 294 and an evaluation is made as to
whether or not the rest of the heart is "captured" in response.
With some techniques, prior to ablating the connective lesions 290,
292, a pacing energy sufficient to capture the heart is applied and
the corresponding power settings are recorded. The exit block test
can then consist of a determination as to whether the heart is
"captured" at the same power settings. When the heart cannot be
captured using the same pre-ablation power settings, an initial
determination can be made that the conductive block 294 was
successful in isolating the target site. In other embodiments, if
capture is not achieved at the pre-ablation power settings, the
power output can then be increased (e.g., doubled) and a
determination made as to whether the heart is "captured" at this
increased power output. If capture is not achieved at this double
power heart pacing, the conductive block 294 can be considered to
be isolated and exit blocking from this area proven. Conversely,
where the heart is captured during the post-ablation exit block
test, an indication is given that the ablation lesion patterns 270,
272, 290, 292 were not successful in isolating the target site 294,
and the surgeon can then repeat the ablation procedure and/or form
additional lesion pattern(s) in other areas.
[0057] An entrance block test can also or alternatively be used to
evaluate the effectiveness of the ablation patterns 270, 272, 290,
292. In particular, the controller 26 (FIG. 1) operates the
auxiliary electrodes 56, 58 to sense electrical activity within the
conductive block 294. The monitored output may be recorded and
saved as a visual "ECG" type output and the collection of monitored
information visually compared to each other. Alternatively or in
addition, an algorithm can be programmed to the controller 26 and
used to compare the captured output; if the difference between the
electrical activity prior to the ablation (e.g., atrial P-wave) is
reduced a significant amount (e.g., 80% reduction), it can be
assumed that the target site 294 has been successfully blocked.
Conversely, if an insignificant difference is determined,
additional lesion patterns can be formed. Additionally or
alternatively, with the auxiliary electrodes 56, 58 being operated
by the controller 26 in a sensing mode, a pacing energy is applied
to the heart outside of the conductive block region 294. If the
auxiliary electrodes 56, 58 (otherwise in contact with epicardial
tissue inside of the conductive block 294) do not sense the
so-applied pacing energy, it can be positively concluded that
entrance block has been achieved.
[0058] In some embodiments, the controller 26 (FIG. 1) can be
programmed with set confirmation parameters and operate to
automatically alert the surgeon as to the results of the conduction
block testing. For example, following ablation with the ablation
electrodes 52, 54 (FIG. 3) as described above, the controller 26
can automatically perform one or more of the pacing/sensing tests.
If the results of one or more of these tests (e.g., the pre- and
post-ablation atrial P-wave comparison test described above) are
viewed by the controller 26 as being indicative of unsuccessful
conduction block, the indicator device 260 (FIG. 2) is operated to
provide a warning to the surgeon (e.g., a red light). Conversely,
when the controller 26 deems the test result(s) as implicating
successful conduction block, the indicator device 260 is operated
by the controller 26 to provide a confirmation to the surgeon
(e.g., a green light). Other indicating techniques can be employed
(e.g., graphical display, audible noise, etc.). Alternatively, the
indicator device 260 can be omitted.
[0059] While the head assembly 40 (FIG. 3) has been described as
having the first and second ablation electrodes 52, 54 (FIG. 3)
with the shapes described above, other configurations are also
acceptable. For example, FIG. 1 1A is a simplified view of another
head assembly 300 in accordance with principles of the present
disclosure and useful with the ablation instrument 22 (FIG. 1). The
head assembly 300 generally includes a paddle body 302, ablation
electrodes 304a-304d, and auxiliary electrodes 306a, 306b. The
paddle body 302 is sized and shaped for a subxiphoid surgical
approach to the posterior left atrium, and can have the wedge-like
shape as shown. The electrodes 304a-306b are maintained by, and are
exteriorly exposed relative to a contact face 308 of, the paddle
body 302 in a spatially fixed manner. The ablation electrodes
304a-304d are akin to the ablation electrodes 52, 54 described
above and are segmented about (and in close proximity to) a
perimeter of the paddle body 302a-302d. The auxiliary electrodes
306a, 306b are akin to the auxiliary electrodes 56, 58 (FIG. 3)
described above, and are located within a perimeter of the ablation
electrodes 304a-304d for performing pacing/sensing operations as
described above. In other embodiments, the auxiliary electrodes
306a, 306b can be omitted. During use, the contact face 308 is
directed against targeted tissue and the ablation electrodes
304a-304d sequentially energized to ablate a portion of a
conductive block region, for example along epicardial tissue of the
posterior left atrium between the left and right pulmonary vein
junctions to interconnect superior and inferior aspects of
separately-formed island lesions. Other features described above
(e.g., suction regions, liquid supply/cooling, etc.) can be
optionally incorporated into the head assembly 300.
[0060] Another embodiment of a head assembly 310 in accordance with
principles of the present disclosure and useful with the ablation
instrument 22 (FIG. 1) is shown, in simplified form, in FIG. 11B.
The head assembly 310 includes a paddle body 312, primary ablation
electrodes 314a-314d, a secondary ablation electrode 316, and
auxiliary electrodes 318a, 318b. The paddle body 312 is sized and
shaped for delivery to the posterior left atrium via a subxiphoid
surgical approach, and can have the wedge-like shape as shown. The
electrodes 314a-318b are maintained by, and are exteriorly exposed
relative to a contact face 320 of, the paddle body 312 in a
spatially fixed manner. The primary ablation electrodes 314a-314d
are segmented about (and in close proximity to) a perimeter of the
paddle body 312, and are akin to the ablation electrodes previously
described. The secondary ablation electrode 316 is arranged
generally parallel with, but spaced from, the first primary
ablation electrode 314a (i.e., a linear distance between the
secondary ablation electrode 316 and the fourth primary ablation
electrode 314d is less than a linear distance between the first
primary ablation electrode 314a and the fourth primary ablation
electrode 314d). The auxiliary electrodes 318a, 318b are akin to
the auxiliary electrodes described above, and are positioned within
a perimeter defined by the second-fourth primary ablation
electrodes 314b-314d and the secondary ablation electrode 316 for
performing pacing/sensing protocols as described above. In other
embodiments, the auxiliary electrodes 318a, 318b can be omitted.
During use, the contact face 320 is directed against targeted
epicardial tissue and the primary ablation electrodes 314a-314d
sequentially energized to create a portion of a conductive block
lesion pattern, for example along epicardial tissue of the
posterior left atrium between the left and right pulmonary vein
junctions to interconnect superior and inferior aspects of
separately-formed island lesions. In instances where the anatomy of
the patient's heart is such that the first primary ablation
electrode 314a is too close to certain anatomical structures (e.g.,
the AV groove), the secondary ablation electrode 316 can be
energized instead of the first primary ablation electrode 314a.
Other features described above (e.g., suction regions, liquid
supply/cooling, etc.), can optionally be incorporated into the head
assembly 310.
[0061] Another embodiment head assembly 330 in accordance with
principles of the present disclosure and useful with the ablation
instrument 22 (FIG. 1) is shown, in simplified form, in FIG. 11C.
The head assembly 330 includes a paddle body 332, ablation
electrodes 334a-334d, and auxiliary electrodes 336a, 336b. The
paddle body 332 is akin to the configurations described above, and
can have a generally wedge-like shape for interfacing with the
posterior left atrium via a subxiphoid surgical approach. With the
construction of FIG. 11C, however, opposing sides 338a, 338b of the
paddle body 332 flare radially outwardly (as compared to the shape
of FIGS. 11A and 11B). Regardless, the electrodes 334a-336b are
maintained by, and exteriorly exposed relative to a contact face
340 of, the paddle body 332 in a spatially fixed manner. The
ablation electrodes 334a-334d are akin to those above and are
segmented about (and in close proximity to) a perimeter of the
paddle body 332, including the flared edges 338a, 338b. With this
construction, when the contact face 340 is positioned against the
posterior left atrium between the left and right pulmonary vein
junctions, the second and third ablation electrodes 334b, 334c are
more likely positioned to intersect with the pulmonary vein island
ablation patterns (e.g., the island lesions 270, 272 of FIG. 9B).
The auxiliary electrodes 336a, 336b are akin to the auxiliary
electrodes described above, and can be operated to perform various
pacing and/or sensing protocols. In other embodiments, the
auxiliary electrodes 336a, 336b can be omitted. Other features
described above (e.g., suction regions, liquid supply/cooling,
etc.) can optionally be incorporated into the head assembly
330.
[0062] Yet another embodiment of a head assembly 350 in accordance
with principles of the present disclosure and useful with the
ablation instrument 22 (FIG. 1) is shown, in simplified form, in
FIG. 11D. The head assembly 350 includes a paddle body 352,
ablation electrodes 354a-354d, and auxiliary electrodes 356a, 356b.
The paddle body 352 is sized and shaped for delivery to the
posterior left atrium via a subxiphoid surgical approach, and can
have the generally oval-like shape reflected in FIG. 11D. The
electrodes 354a-356b are maintained by, and exteriorly exposed
relative to a contact face 358 of, the paddle body 352 in a
spatially fixed manner. The ablation electrodes 354a-354d are
segmented about (and in close proximity to) a perimeter of the
paddle body 352, and are otherwise akin to the ablation electrodes
described above. The auxiliary electrodes 356a-356b are optional,
and are akin to the auxiliary electrodes described above for
performing one or more pacing/sensing protocols. During use, the
contact face 358 is directed against targeted epicardial tissue and
the ablation electrodes 354a-354d sequentially energized to ablate
a portion of a conductive blank region, for example, along
epicardial tissue of the posterior left atrium between the
pulmonary vein junctions to interconnect superior and inferior
aspects of separately-formed island lesions. Other features
described above (e.g., suction regions, liquid supply/cooling,
etc.) can optionally be incorporated into the head assembly
350.
[0063] Yet another embodiment head assembly 360 in accordance with
principles of the present disclosure and useful with the ablation
instrument 22 (FIG. 1) is shown, in simplified form, in FIG. 11E.
The head assembly 360 includes a paddle body 362, ablation
electrodes 364a-364c, a first pair of auxiliary electrodes 366a,
366b and a second pair of auxiliary electrodes 368a, 368b. The
paddle body 362 is sized and shaped for delivery to the posterior
left atrium via a subxiphoid surgical approach, and can have the
wedge-like shape as shown. The electrodes 364a-368b are maintained
by, and are exteriorly exposed relative to a contact face 370 of,
the paddle body 362 in a spatially fixed manner. The ablation
electrodes 364a-364c are mounted to the paddle body 362 in a
segmented fashion, generally defining the Z-like pattern shown. For
example, the first and third ablation electrodes 364a, 364c can be
generally parallel to one another, with the second ablation
electrode 364b extending from the first ablation electrode 364a at
a first side of the paddle body 362 to the third ablation electrode
364c at an opposite side of the paddle body 362. The auxiliary
electrode pairs 366a, 366b, 368a, 368b are located at opposite
sides of the second ablation electrode 364b. With this
construction, the contact face 370 can be directed into contact
with epicardial tissue of the posterior left atrium via a
subxiphoid surgical approach, with the first and third ablation
electrodes 364a, 364c being sequentially energized to form lesions
that interconnect superior and inferior aspects of
separately-formed formed island ablation patterns as described
above. The second ablation electrode 364b also defines an ablation
lesion, with the auxiliary electrode pairs 366a, 366b and 368a,
368b being operated to evaluate desired conduction block. Other
features described above (e.g., suction regions, liquid
supply/cooling, etc.) can optionally be incorporated into the head
assembly 360.
[0064] Another alternative head assembly 380 in accordance with
principles of the present disclosure and useful with the ablation
instrument 22 (FIG. 1) is shown, in simplified form, in FIG. 11F.
The head assembly 380 includes a paddle body 382, ablation
electrodes 384a-384c, a first pair of auxiliary electrodes 386a,
386b and a second pair of auxiliary electrodes 388a, 388b. The head
assembly 380 is highly akin to the head assembly 360 (FIG. 11E)
described above, with the paddle body 382 being sized and shaped to
access the posterior left atrium via a subxiphoid surgical
approach. With the construction of FIG. 11F, however, the paddle
body 382 has a clover-like shape with flared sides. The electrodes
384a-388b are maintained by, and exteriorly exposed relative to a
contact face 390 of, the paddle body 382 in a spatially fixed
manner. The first and third ablation electrodes 384a, 384c extend
along (and in close proximity to) portions of a perimeter of the
paddle body 382 as shown, with the second ablation electrode 384b
extending in the angular fashion shown (segmented from the first
and third ablation electrodes 384a, 384c). The auxiliary electrode
pairs 386a, 386b and 388a, 388b are arranged at opposite sides of
the second ablation electrode 384b, and are operable to perform
various pacing and sensing protocols. During use, the contact face
390 is directed against target epicardial tissue and the ablation
electrodes 384a-384c sequentially energized to ablate a portion of
a conductive block pattern, for example along epicardial tissue of
the posterior left atrium between the pulmonary vein junctions to
interconnect superior and inferior aspects of separately-formed
island ablation regions. Other features described above (e.g.,
suction regions, liquid supply/cooling, etc.) can optionally be
incorporated into the head assembly 380.
[0065] Another embodiment head assembly 400 in accordance with
principles of the present disclosure and useful with the ablation
instrument 22 (FIG. 1) is shown, in simplified form, in FIG. 11G.
The head assembly 400 includes a paddle body 402, ablation
electrodes 404a-404f, and auxiliary electrodes 406a, 406b. The
paddle body 402 is sized and shaped for delivery to the posterior
left atrium via a subxiphoid approach, and can have the clover-like
shape shown. The electrodes 404a-406b maintained by, and are
exteriorly exposed relative to a contact face 410 of, the paddle
body 402 in a spatially fixed manner. The ablation electrodes
404a-404f are mounted in a segmented fashion about (and in close
proximity to) a perimeter of the paddle body 406. Finally, the
auxiliary electrodes 406a, 406b are akin to the auxiliary
electrodes described above, and are disposed within an area defined
by a pattern of the ablation electrodes 404a-404f. Alternatively,
the auxiliary electrodes 406a, 406b can be omitted. With the
clover-like shape of the paddle body 402, upon placement of the
contact face 410 against epicardial tissue of the posterior left
atrium between the pulmonary vein junctions, the second and seventh
ablation electrodes 404b, 404f are better positioned to more likely
intersect with island lesions as previously described. Other
features described above (e.g., suction regions, liquid
supply/cooling, etc.) can optionally be incorporated into the head
assembly 400.
[0066] Yet another embodiment head assembly 420 in accordance with
principles of the present disclosure and useful with the ablation
instrument 22 (FIG. 1) is shown, in simplified form, in FIG. 11H.
The head assembly 420 includes a paddle body 422, primary ablation
electrodes 424a-424d, secondary ablation electrodes 426a-426d, and
auxiliary electrode pairs 428a-428e. The paddle body 422 is sized
and shaped for delivery to the posterior left atrium via a
subxiphoid surgical approach, and can have the wedge-like shape
shown. The electrodes 424a-428e are maintained by, and are
exteriorly exposed relative to a contact face 430 of, the paddle
body 422 in a spatially fixed manner. The primary ablation
electrodes 424a-424d are mounted in a segmented fashion about (and
in close proximity to) a perimeter of the paddle body 422. The
secondary ablation electrodes 426a-426d extend generally parallel
with the first primary ablation electrode 424a in a spaced apart
fashion. Respective ones of the auxiliary electrode pairs 428a-428e
are arranged as shown. During use, the contact face 430 is directed
against targeted epicardial tissue and some or all of the ablation
electrodes 424a-424d and 426a-426d are sequentially energized to
ablate corresponding lesion patterns, for example at the posterior
left atrium to interconnect superior and inferior aspects of
separately-formed pulmonary vein island lesions. Various ones of
the auxiliary electrode pairs 428a-428e can be selectively operated
to perform various pacing and sensing protocols to evaluate
conduction blockage of the resultant lesion pattern. Alternatively,
one or more of the auxiliary electrode pairs 428a-428e can be
omitted. Other features described above (e.g., suction regions,
liquid supply/cooling, etc.) can optionally be incorporated into
the head assembly 420.
[0067] Another head assembly 440 in accordance with principles of
the present disclosure and useful with the ablation instrument 22
(FIG. 1) is shown, in simplified form, in FIG. 11I. The head
assembly 440 includes a paddle body 442, ablation electrodes
444a-444d, and an auxiliary electrode pair 446a-446b. The paddle
body 442 is sized and shaped for delivery to the posterior left
atrium via a subxiphoid surgical approach, and can have the
wedge-like shown. In contrast to other embodiments, opposing sides
448a, 448b of the paddle body 442 have a concave shape. With this
construction, the opposing sides 448a, 448b may more readily tit
between the right and left pulmonary vein junctions, for example
with the left atrium. Regardless, the electrodes 444a-446b are
maintained by, and are exteriorly exposed relative to a contact
face 450 of, the paddle body 442 in a spatially fixed manner. The
ablation electrodes 444a-444d are akin to previous embodiments, and
are mounted in a segmented fashion about (and in close proximity
to) a perimeter of the paddle body 442. The auxiliary electrodes
446a-446d are also akin to other embodiments, and are generally
disposed within a pattern defined by the ablation electrodes
444a-444d. The head assembly 440 can be operated in a manner akin
to previous descriptions, with the contact face 450 being directed
against targeted epicardial tissue, for example along the posterior
left atrium between the pulmonary vein junctions and the ablation
electrodes 444a-444d sequentially energized to ablate a portion of
a conductive block pattern, for example interconnecting superior
and inferior aspects of separately-formed island ablation regions.
Other features described above (e.g., suction regions, liquid
supply/cooling, etc.) can optionally be incorporated into the head
assembly 440.
[0068] Yet another embodiment head assembly 460 in accordance with
principles of the present disclosure and useful with the ablation
instrument 22 (FIG. 1) is shown, in simplified form, in FIG. 11J.
The head assembly 460 includes a paddle body 462, ablation
electrodes 464a, 464b and auxiliary electrodes 466a, 466b. The
paddle body 462 is sized and shaped for delivery to the posterior
left atrium via a subxiphoid surgical approach. With the
construction of FIG. 11J, a trailing region 468 of the paddle body
462 forms or defines transverse protrusions 470a, 470b. The
protrusions 470a, 470b are generally configured to contact or
engage one of the left pulmonary veins and one of the right
pulmonary veins, respectively, when the head assembly 460 is
otherwise positioned along the posterior left atrium. Thus, the
protrusions 470a, 470b serve to better ensure desired arrangement
of the head assembly 460 along the posterior left atrium. The
electrodes 464a-466b are maintained by, and exteriorly exposed
relative to a contact face 472 of, the paddle body 462 in a
spatially fixed manner. The ablation electrodes 464a, 464b are akin
to previous embodiments, and are arranged in a spaced apart
fashion. The auxiliary electrode 466a, 466b are akin to previous
embodiments, and are mounted to the paddle body 462 between the
ablation electrodes 464a, 464b. During use, the contact face 472 is
directed into contact with epicardial tissue of the posterior left
atrium, with the protrusions 470a, 470b engaging respective ones of
the left and right pulmonary veins. The ablation electrodes 464a,
464b are sequentially energized to ablate a portion of a conductive
block pattern, for example interconnecting superior and inferior
aspects of separately-formed island ablation regions as described
above. Where provided, the auxiliary electrodes 486a, 486b are
employed to perform various pacing/sensing protocols. Other
features described above (e.g., suction regions, liquid
supply/cooling, etc.) can optionally be incorporated into the head
assembly 460.
[0069] Another embodiment head assembly 480 in accordance with
principles of the present disclosure and useful with the ablation
instrument 22 (FIG. 1) is shown, in simplified form, in FIG. 11K.
The head assembly 480 includes a paddle body 482, ablation
electrodes 484a, 484b, and auxiliary electrodes 486a, 486b. The
paddle body 482 is sized and shaped for delivery to the posterior
left atrium via a subxiphoid surgical approach, and can have the
wedge-like shape shown. The electrodes 484a-486b are maintained by,
and are exteriorly exposed relative to a contact face 488 of, the
paddle body 482 in a spatially fixed manner. The ablation
electrodes 484a, 484b extend in a generally parallel fashion at
opposite ends of the paddle body 482, and the auxiliary electrodes
486a, 486b are located between the ablation electrodes 484a, 484b.
The head assembly 480 is operable in manners similar to those
described above, with the contact face 488 being directed against
epicardial tissue of the posterior left atrium between the
pulmonary vein junctions. The ablation electrodes 484a, 484b are
sequentially energized to ablate a portion of a conductive block
pattern, for example interconnecting superior and inferior aspects
of separately-formed island ablation regions. The auxiliary
electrodes 486a, 486b can be used for various pacing/sensing
protocols, but can be omitted. Other features described above
(e.g., suction regions, liquid supply/cooling, etc.) can optionally
be incorporated into the head assembly 480.
[0070] Another embodiment head assembly 490 in accordance with
principles of the present disclosure and useful with the ablation
device 22 (FIG. 1) is shown, in simplified form, in FIG. 11L. The
head assembly 490 includes a paddle body 492, ablation electrodes
494a, 494b, and auxiliary electrodes 496a, 496b. The paddle body
492 is sized and shaped for delivery to the posterior left atrium
via a subxiphoid surgical approach, and can have the oval-like
shape shown. The electrodes 494a-496b are maintained by, and are
exteriorly exposed relative to a contact face 498 of, the paddle
body 492 in a spatially fixed manner. The ablation electrodes 494a,
494b extend in a generally parallel fashion at opposite ends of the
paddle body 492. The auxiliary electrodes 496a, 496b are mounted to
the paddle body 492 between the ablation electrodes 494a, 494b. The
head assembly 490 is operable to perform various ablation
procedures as described above, including the contact face 498 being
directed against epicardial tissue of the posterior left atrium
between the pulmonary vein junctions. The ablation electrodes 496a,
496b are sequentially energized to ablate a portion of a conductive
block pattern, for example interconnecting superior and inferior
aspects of separately-formed island ablation regions. The auxiliary
electrodes 496a, 496b can be used for various pacing/sensing
protocols, but can be omitted. Other features described above
(e.g., suction regions, liquid supply/cooling, etc.) can optionally
be incorporated into the head assembly 490.
[0071] Another embodiment head assembly 500 in accordance with
principles of the present disclosure and useful with the ablation
device 22 (FIG. 1) is shown, in simplified form, in FIG. 11M. The
head assembly 500 includes a paddle body 502, ablation electrodes
504a, 504b, and auxiliary electrodes 506a, 506b. The paddle body
502 is sized and shaped for delivery to the posterior left atrium
via a subxiphoid surgical approach, and can have the generally
circular shape shown. The electrodes 504a-506b are maintained by,
and are exteriorly exposed relative to a contact face 508 of, the
paddle body 502 in a spatially fixed manner. The ablation
electrodes 504a, 504b are arranged in a segmented fashion about
(and in close proximity to) a perimeter of the paddle body 502. The
auxiliary electrodes 506a, 506b are located between or
circumscribed by the ablation electrodes 504a, 504b. The head
assembly 500 is operable in manners similar to those described
above, with the contact face 508 being directed against epicardial
tissue of the posterior left atrium between the pulmonary vein
junctions. The ablation electrodes 504a, 504b are sequentially
energized to ablate a corresponding lesion pattern, for example a
lesion pattern interconnecting separately-formed pulmonary vein
island lesions. The auxiliary electrodes 506a, 506b can be operated
to perform various pacing and/or sensing procedures, or can be
omitted. Other features described above (e.g., suction regions,
liquid supply/cooling, etc.) can optionally be incorporated into
the head assembly 500.
[0072] Another embodiment head assembly 510 in accordance with
principles of the present disclosure and useful with the ablation
device 22 (FIG. 1) is shown, in simplified form, in FIG. 11N. The
head assembly 510 includes a paddle body 512, ablation electrodes
514a-514c, and auxiliary electrodes 516a, 516b. The paddle body 512
is sized and shaped for delivery to the posterior left atrium via a
subxiphoid surgical approach, and can have the wedge-like shape
shown. The electrodes 514a-516b are maintained by, and are
exteriorly exposed relative to a contact face 518 of, the paddle
body 512 in a spatially fixed manner. The ablation electrodes
514a-514c are arranged in a segmented fashion, defining a C-like
pattern as shown. The auxiliary electrodes 516a, 516b are located
along the paddle body 512 essentially within the C-like pattern.
The head assembly 510 can be employed to perform various ablation
and other procedures in ways consistent with previous descriptions,
including the contact face 518 being directed against epicardial
tissue of the posterior left atrium between the pulmonary vein
junctions. The ablation electrodes 514a-514c are sequentially
energized to ablate a portion of a conductive block pattern, for
example interconnecting superior and inferior aspects of
separately-formed island lesions. Other features described above
(e.g., suction regions, liquid supply/cooling, etc.) can optionally
be incorporated into the head assembly 510.
[0073] Another embodiment head assembly 520 in accordance with
principles of the present disclosure and useful with the ablation
device 22 (FIG. 1) is shown, in simplified form, in FIG. 11O. The
head assembly 520 includes a paddle body 522, primary ablation
electrodes 524a-524c, secondary ablation electrodes 526a-526c, a
first auxiliary electrode pair 528a, 528b, and a second auxiliary
electrode pair 530a, 530b. The paddle body 522 is sized and shaped
for delivery to the posterior left atrium via a subxiphoid surgical
approach, and can have the wide, wedge-like shape shown. In
particular, the paddle body 522 defines opposing sides 532a, 532b,
with the first side 532a being longer than the second side 532b.
The electrodes 524a-530b are maintained by, and are exteriorly
exposed relative to a contact face 534 of, the paddle body 522 in a
spatially fixed manner. The primary ablation electrodes 524a-524c
are arranged in the Z-like pattern shown. The secondary ablation
electrodes 526a-526c are also mounted to the paddle body 522 in a
segmented fashion, but extend along the first side 532a. With this
arrangement, upon deployment of the head assembly 520 along the
posterior left atrium, the secondary ablation electrodes 526a-526c
can be energized to create a lesion pattern between the superior
vena cava and the inferior vena cava. Stated otherwise, the head
assembly 520 can be employed to form connective lesions between the
superior and inferior aspects of separately-formed pulmonary vein
island lesions as previously described, whereas the secondary
ablation electrodes 526a-526c are utilized, with corresponding
re-positioning of the contact face 534, to define another portion
of the MAZE pattern. Regardless, the auxiliary electrode pairs
528a, 528b and 530a, 530b are operable in manners akin to previous
descriptions for performing various pacing and/or sensing
operations. Other features described above (e.g., suction regions,
liquid supply/cooling, etc.) can optionally be incorporated into
the head assembly 520.
[0074] Another embodiment head assembly 540 in accordance with
principles of the present disclosure and useful with the ablation
device 22 (FIG. 1) is shown, in simplified form, in FIG. 11P. The
head assembly 540 includes a paddle body 542, primary ablation
electrodes 544a, 544b, secondary ablation electrodes 546a, 546b,
tertiary ablation electrodes 548a, 548b, and three pairs of
auxiliary electrodes 550a-550c. The paddle body 542 is sized and
shaped for delivery to the posterior left atrium via a subxiphoid
surgical approach, and can have the circular-like shape shown. The
electrodes 544a-550c are maintained by, and are exteriorly exposed
relative to a contact face 552 of, the paddle body 542 in a
spatially fixed manner. The primary electrodes 554a, 554b are
arranged in a segmented fashion at a perimeter of the paddle body
542. Thus, the primary ablation electrodes 544a, 544b define a
circle-like pattern. The secondary ablation electrodes 546a, 546b
are also arranged in a segmented fashion to define a circular-like
pattern, but are located within, and spaced from, the primary
ablation electrodes 544a, 544b. The tertiary ablation electrodes
548a, 548b are within, and spaced from, the circular pattern of the
secondary ablation electrodes 546a, 546b. Finally, the auxiliary
electrode pairs 560a-560c are mounted to the paddle body 542
between the circular patterns of the ablation electrodes 544a-548b
as shown. Desired lesion patterns can be generated by directing the
contact face 552 against targeted epicardial tissue of the
posterior left atrium and sequentially energizing respective ones
of the ablation electrode 544a-548d. For example, the primary
ablation electrodes 544a, 544b can be energized to form a lesion
pattern that interconnects superior and inferior aspects of
separately-formed pulmonary vein island lesions. The auxiliary
electrode pairs 560a-560c are operable in manners akin to those
previously described, facilitating various pacing and/or sensing
procedures. Other features described above (e.g., suction regions,
liquid supply/cooling, etc.) can optionally be incorporated into
the head assembly 540.
[0075] Another embodiment head assembly 570 in accordance with
principles of the present disclosure and useful with the ablation
device 22 (FIG. 1) is shown, in simplified form, in FIG. 11Q. The
head assembly 570 includes a paddle body 572, ablation electrodes
574a-574c, and auxiliary electrodes 576a, 576b. The paddle body 572
is sized and shaped for delivery to the posterior left atrium via a
subxiphoid surgical approach, and can have the wedge-like shape
shown. In addition, the paddle body 572 forms or defines a cooling
zone 578, for example as an internal pocket within the paddle body
572. Tubing 580 is fluidly connected to the cooling zone 578, and
serves to deliver a cooling liquid (e.g., saline) to the cooling
zone 578. The electrodes 574a-576b are maintained by, and
exteriorly exposed relative to a contact face 582 of, the paddle
body 572 in a spatially fixed manner. The ablation electrodes
574a-574d are arranged along (and in close proximity to) a
perimeter of the paddle body 572. The auxiliary electrodes 576a,
576b are located along the paddle body 572 within a pattern defined
by the ablation electrodes 574a-574c. During use, the head assembly
570 is operable in manners akin to those previously described, with
the contact face 582 being directed against targeted epicardial
tissue of the posterior left atrium between the pulmonary vein
junctions. The ablation electrodes 574a-574d are sequentially
energized to ablate a desired lesion pattern into contacted tissue.
The auxiliary electrodes 576a, 576b facilitate the performance of
various pacing and/or sensing procedures. In addition, a cooling
liquid can be provided to and/or circulate within the cooling zone
578 as desired to effectuate cooling of contacted anatomy (e.g.,
the circumflex artery).
[0076] Another embodiment head assembly 590 in accordance with
principles of the present disclosure and useful with the ablation
device 22 (FIG. 1) is shown, in simplified form, in FIG. 11R. The
head assembly 590 includes a paddle body 592, ablation electrodes
594a-594c, and two pairs of auxiliary electrodes 596a, 596b. The
paddle body 592 is sized and shaped for delivery to the posterior
left atrium via a subxiphoid surgical approach, and can have the
wedge-like shape shown. The electrodes 594a-596b are maintained by,
and are exteriorly exposed relative to a contact face 598 of, the
paddle body 592. The ablation electrodes 594a-594c are arranged in
the Z-like pattern shown. In this regard, skirts 600a-600c are
formed or provided about respective ones of the ablation electrodes
594a-594c, and establish corresponding suction regions 602a-602c. A
negative pressure source (not shown) is fluidly connected to each
of the suction regions 602a-602c; upon application of negative
pressure, tissue otherwise in contact with the skirts 600a-600c is
pulled or suctioned into intimate contact with the corresponding
ablation electrodes 592a-592c. Thus, operation of the head assembly
590 in performing an ablation procedure is akin to previous
descriptions, including the contact face 598 being directed against
targeted epicardial tissue of the posterior left atrium between the
pulmonary vein junctions. Tissue to be ablated is suctioned into
contact with the selected ablation electrode 592a-592c and
sequentially ablated. The auxiliary electrode pairs 596a, 596b are
operable in manners akin to previous descriptions, and can
facilitate various pacing and/or sensing procedures.
[0077] The ablation instruments, systems, and methods of the
present disclosure provide a marked improvement over previous
designs. By promoting ready access to, and ablative contact with,
epicardial tissue of the posterior left atrium via a subxiphoid
surgical approach, procedures can be performed in ways not
heretofore available. The subxiphoid approach is a midline skin
incision that avoids the division of major muscle groups or bone.
The incision is made inferior to the sternum, such that the extent
of the incision is primarily a cosmetic concern and is without
limitation from surrounding bone. The surgeon has the choice of how
long of an incision to apply in order to achieve proper visibility
of the targeted tissue site. The incision may be easily widened
using standard and/or long blade retractors. Regardless, a desired
portion of a MAZE lesion pattern is easily formed with the ablation
instrument of the present disclosure, forming desired posterior
aspect pulmonary vein island lesion interconnections. Further, in
some embodiments, a so-formed conduction block can be readily
evaluated with the ablation instrument.
[0078] Although the present disclosure has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes can be made in form and detail without
departing from the spirit and scope of the present disclosure.
* * * * *